1. Field of the Invention
The invention relates to a semiconductor device and a method of forming the same, and more particularly, to a semiconductor device being formed through a sidewall image transference process and a method of forming the same.
2. Description of the Prior Art
In recent years, as the continuous decrease of the sizes of semiconductor devices and the increase of the stacking and integration density of semiconductor devices, the photolithography process approaches physical limitation such that the costs of design, process development, and photomask rise dramatically. Therefore, many traditional process and fabrication method cannot meet the fabrication requirement anymore. In current techniques, in order to achieve sub-lithographic features, an immersion photolithography process in corporation with the argon fluoride (ArF) laser tool is performed for further improve the resolution. In addition, the manufacturer also provides self-aligned double-patterning (SADP) process, also known as sidewall image transfer (SIT) technique, to form required microminiature components.
Generally, the sidewall image transfer process includes firstly forming a plurality of sacrificial patterns on a substrate, wherein the dimension of such sacrificial patterns is substantially greater or equal to the critical dimension of photolithography. Then, spacers are formed on sidewalls of the sacrificial patterns through a deposition and an etching process. Since the dimension of the spacers may be smaller than the critical dimension, patterns of the spacers may be transferred into the substrate by using the spacers as mask to form a smaller fin structure. However, as the size of the semiconductor devices shrink, the electrical and physical requirements in each part of the devices become critical, like the dimensions and shapes of the wiring and the transistor and the spacing therebetween for example. Thus, how to achieve standard requirements and overcome the physical limitations has become an important issue in the industry of the semiconductor.